It is well known that amorphous solids in various shapes, e.g., in the shape of a thin ribbon, a filament, or a powder and granular material, can be produced by rapid solidifying alloys in a molten state. An amorphous alloy thin ribbon can be prepared by various methods, e.g., a single-roll process, a twin-roll process, an in-rotating liquid spinning process, or an atomization process, which can provide high cooling rates. Therefore, a number of Fe-based, Ti-based, Co-based, Zr-based, Ni-based, Pd-based, or Cu-based amorphous alloys have been developed, and properties specific to amorphous alloys, e.g., excellent mechanical properties and high corrosion resistance, have been made clear. For example, with respect to Cu-based amorphous alloys, researches have been made primarily on binary Cu—Ti or Cu—Zr or ternary Cu—Ni—Zr, Cu—Ag-RE, Cu—Ni—P, Cu—Ag—P, or Cu—Mg-RE.
These Cu-based amorphous alloys have a poor glass-forming ability and, therefore, amorphous alloys of only thin ribbon shaped, powder-shaped, fiber-shaped, and the like have been able to be produced by a liquid quenching technique. Since high thermal stability is not exhibited and it is difficult to form into the shape of a final product, industrial applications thereof are significantly limited.
It is known that an amorphous alloy exhibits high stability against crystallization and has a high amorphous-forming ability, the amorphous alloy exhibiting glass transition and having a large supercooled liquid region and a high reduced glass transition temperature (Tg/Tl). Such a bulk-shaped amorphous alloy can be produced by a metal mold casting method. On the other hand, it is known that when an amorphous alloy is heated, transition to a supercooled liquid state is effected before crystallization and a sharp reduction in viscosity is exhibited with respect to a specific alloy system. In such a supercooled liquid state, since the alloy has a reduced viscosity, an amorphous alloy molded article in an arbitrary shape can be produced by a closed forging process or the like. Consequently, it can be said that an alloy having a large supercooled liquid region and a high reduced glass transition temperature (Tg/Tl) has a high amorphous-forming ability and excellent workability.
Research and development on a large size Cu-based amorphous alloy in consideration of practical use, put another way, on a Cu-based amorphous alloy having an excellent amorphous-forming ability and a high Cu content have made little headway. A nonmagnetic elinvar alloy used for an elastic effector has been invented (Patent Document 1), while the alloy is represented by a general formula Cu100-a-b-cMaXbQc (M represents at least one element of Zr, RE, and Ti, X represents at least one element of Al, Mg, and Ni, and Q represents at least one element of Fe, Co, V, Nb, Ta, Cr, Mo, W, Mn, Au, Ag, Re, platinum group elements, Zn, Cd, Ga, In, Ge, Sn, Sb, Si, and B). However, specific examples of compositions include only those containing Cu at contents of a low 40 atomic percent or less, and with respect to the mechanical properties, only an example in which the Vickers hardness (20° C. Hv) is 210 to 485 is reported. Furthermore, a nonmagnetic metal glassy alloy used for strain gauges has been invented (Patent Document 2), while the alloy has an alloy composition similar to this.
In 2001, the inventors of the present invention developed a Cu-based Cu—Zr—Ti and Cu—Hf—Ti amorphous alloys having an excellent amorphous-forming ability, and applied for a patent (Patent Document 3).    Patent Document 1 Japanese Unexamined Patent Application Publication No. 09-20968    Patent Document 2 Japanese Unexamined Patent Application Publication No. 11-61289    Patent Document 3 WO 02/053791 A1